Method and apparatus for measuring and adjusting the moisture content and therewith the formability of granular material such as foundry sand and the like



March 19, 1968 H. JACOB 3,373,753

METHOD AND APPARATUS FOR MEA URING AND ADJUSTING THE MOISTURE CONTENT AND THEREWITH THE FORMABILITY OF GRANULAR MATERIAL SUCH AS FOUNDRY SAND AND THE LIKE Filed July 29, 1966 Z I 25'} Z F/G 4 INVENTOR 64 7 76L Harm lLnn/w L- m ,4 f, (fr/ker- ATTORNEY United tates 3,373,753 Patented Mar. 19, 1968 3,373,753 METHQD AND APPARATUS FOR MEASURING AND ADJUSTING THE MOISTURE CONTENT AND THEREWITH THE FQRMABILITY F GRANULAR MATERIAL SUCH AS FOUNDRY SAND AND TIE LIKE Hermann Jacob, Facheufelderweg 115, Horst, Kreis Maschen, Germany Filed July 29, 1966, Ser. No. 568,864 Claims priorit application Germany, July 31, 1965, 3 28,692 14 Claims. (Cl. 134-18) The present invention relates to a method for measuring and adjusting the moisture content and therewith the formability of granular material such as foundry sand and the like.

' If granular material such as foundry sand and the like is dropped in a thin stream onto a substantially horizontal surface it will form a cone of a given c one angle which will depend on the angle of repose of the fiowable granular material, which angle of repose will in turn depend, for a given grain size of the granular material, on the moisture content of this material. When the base of the cone is kept at a predetermined radius, the height of the thus formed cone of granular material will obviously be proportional to the moisture content of this material.

The method and apparatus according to the present invention for measuring and adjusting the moisture content and therewith the formability of granular material such as foundry sand and the like are based on the above acts, which may be used for measuring and adjusting the moisture content of granular material during continuous transporting thereof for instance from a point of storage to a point of use.

It is an object of the present invention to provide for a method for measuring and adjusting the moisture content of granular material and to provide for an apparatus for carrying out the method of the present invention.

It is a further object of the present invention to provide for an apparatus of the aforementioned kind which is of simple construction and which permits measuring and adjusting the moisture content of granular material as the latter is continuously transported.

With these objects in view, the method in accordance with the present invention for measuring and adjusting the moisture content of granular material such as foundry sand and the like mainly comprises the steps of dropping the granular material in moist condition and in a thin stream onto a surface extending substantially normal to said stream, continuously moving the surface in a direction substantially normal to the stream so that the material will form on the surface a continuous pile of triangular cross section in which the angles of the triangular cross section will depend on the angle of repose of the material, which in turn will be proportional to the moisture content of the material, maintaining the base of the aforementioned pile on the surface at a constant preselected width so that the height of the pile will be proportional to the angle of repose, measuring the height of the pile thus formed, and regulating the moisture content of the material before dropping it on the aforementioned surface in dependence on the measured height of the pile.

The apparatus for carrying out the method according to the present invention mainly comprises elongated transporting means having an upper substantially horizontal surface and being movable in substantially horizontal di rection, feeding means for dropping granular material in a stream of material from above onto the upper surface of the transporting means while continuously moving the latter in the aforementioned direction so that the material will form on the transporting means a continuous pile of triangular cross section having its base on the aforementioned surface, engaging means engaging the pile in the region of its base so as to maintain the width of the base at a given preselected constant width, whereby the height of the pile will depend on the angle of repose of the moist granular material, measuring means for measuring the height of the pile at a location spaced in the aforementioned direction from the engaging means, and means in the region of said feeding means connected to and cooperating with the measuring means for feeding a moistening agent into the material for regulating the moisture content thereof before dropping the material onto the upper surface of the transporting means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional ob ects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic side view of the apparatus according to the present invention;

FIG. 2 is a top view of the apparatus shown in FIG. 1 with certain elements of the apparatus removed for the sake of clarity;

FIG. 3 is a transverse cross section taken along the line 3-3 of FIG. 1 and being drawn to an enlarged scale; and

FIG. 4 is a transverse cross section taken along the line 4-4 of FIG. 1 and likewise drawn to an enlarged scale.

Referring now to the drawing and more particularly to FIGS. 1 and 2 of the same, it will be seen that the apparatus according to the present invention comprises elongated transporting means 3, including support means which may comprise a pair of elongated U-beams 5 extending spaced from and parallel to each other in substantially horizontal direction and connected to a frame or the like not shown in the drawing, a pair of spaced rollers 4 turnably mounted on bearings 5a mounted on the beams 5 and an endless transporting band 6 wound about the rollers 4, so that the upper run of the endless band will move in direction of the arrow shown in FIG. 1 when one of the rollers 4 is driven in clockwise direction by means not shown in the drawing. The band 6 has a portion 6a of relatively great width and small thickness and a central portion 6b extending longitudinally of the band and having a thickness considerably greater than the section 6a and a preselected width w (FIG. 4). The band portions 6:: and 6b are preferably integrally formed for instance from rubber.

The apparatus includes further feedingmeans for dropping granular material such as foundry sand or the like in a stream of material onto a central portion of the upper surface of the portion 612 of the endless band 6. The feeding means may include a container or hopper 1 arranged above and in the region of the left end, as viewed in FIG. 1, of the upper run of the band 6 from which a stream S passes onto a vibrating sieve 2 located beneath the outlet end of the container 1 and above the upper surface of the upper run of the band 6, from where the stream of sand S passes onto a central region of the moving band 6 to thus form a pile of sand P, as shown in FIG. 3. The sieve 2 is mounted and vibrated by known means not shown in the drawing. This pile of sand P will spill over the side faces of the raised band portion 6b so that lateral portions of the pile P will also form on the upper surface of the wide band portion 6a.

Engaging means are provided which engage the pile P within the region of its base so as to maintain on the upper surface of the raised band portion 612 a pile of sand P of triangular cross section having a width equal to the width w of the raised band portion 612. The aforementioned engaging means preferably comprise stripper means including a pair of limiting bars 7 having each, as best shown in FIGS. 3 and 4, an upper preferably beveled edge 7, slightly above the upper horizontal surface of the raised band portion 6b. The bars 7 extend longitudinally along opposite side faces of the raised band portion 6b and the bars 7 are mounted by means not shown in the drawing adjustable in vertical direction but immovable in longitudinal direction. The stripper means include further a plurality of stripper bars 711 respectively extending from outer faces of the bars 7 inclined at an acuate angle with respect thereto.

The apparatus includes further measuring means 8 for measuring the height of the pile P having at its base a width w equal to the width of the raised band portion 6b. The measuring means 8 include at least one, but preferably a plurality, for instance four, as shown in FIG. 1, photoelectric cells 9a, 9b, 9c and 9d which are arranged spaced from each other in direction of movement of the upper run of the band 6 and in such a manner that the vertical distance of successive photo-cells from the upper surface of the raised portion of the band, respectively from the upper edges of the bars 7, increases in direction of movement of the upper run of the band. The photo-cells 9a-9d are mounted on a frame 11 or the like to one side of the pile P and a light source 9' for each photo-cell is mounted on the frame 11 on the other side of the pile, as schematically indicated in FIG. 4, so that the light ray emanating from the light source 9' will either be interrupted by the pile P or, depending on the height of the pile, pass on to the respective photocell so that the latter will give when the light ray is interrupted one signal and a different signal when the light ray passes on to the photo-cell. The frame 11 is adjustable in vertical direction and for this purpose a screw spindle 12 may be provided which is turnably mounted in an upper transverse portion of a U-shaped frame 10 fixed at the lower ends thereof to the beams 5. The spindle 12 carries at its upper end a wheel 12 for turning the spindle about its axis and the lower end of the spindle is connected to the frame 11 in any convenient manner for movement therewith in vertical direction and for turning relative thereto. The frame 11 is preferably guided in the U-shaped frame 10 so that the frame 11 is prevented from turning with the spindle 12 about the axis of the latter.

The apparatus includes further means for regulating the moisture content of the granular material before the latter is dropped onto the upper surface of the transporting band 6. These means may include a plurality of pipes 13a, 13b, 13c and 13:1 for feeding a moistening agent, for instance water, from a non-illustrated reservoir into the container 1, in which preferably mixing means are located to thoroughly mix the water with the sand before the latter leaves the outlet end of the container. Valves 14a, 14b, 14c and 14d are respectively located in the pipes 13a-13d for regulating the amount of moistening agent flowing through the respective pipe from one or a plurality of reservoirs of such moistening agents. The valves 14a 14d are respectively connected to the photo-cells 9a-9d in a manner known in the art and not forming part of the present invention so that the valves are respectively opened or closed depending on whether the light from the respective light source impinges onto the respective photo-cell or whether the light ray is interrupted by the pile P passing between the light sources and the photo-cells.

The above-described apparatus will operate as follows:

Granulated material, such as foundry sand or the like, is fed in a continuous stream or intermittently onto the sieve 2 which is vibrated by means known in the art, not shown in the drawing, and which is constructed and arranged in such a manner that the stream of sand passing through the sieve 2 is delivered on a central part of the raised portion 6b of the band 6 which moves continuously in the direction of the arrow shown in FIG. 1 towards the right, as viewed in FIG. 1. Thereby the sand deposited on the band 6 will form a pile P of triangular cross section spilling to opposite sides beyond the upper surface of the band portion 6b and beyond the upper edges of the limiting bars 7, as shown in FIG. 3. As the band 6 moves in direction of the arrow shown in FIG. 1 towards the right, the stripper bars 7a will engage the portions of the elongated pile P located outside the limiting bars 7 so that a pile P of triangular cross section and having a width equal to the width of the raised portion 612 of the band and a pair of deflected streams of sand P will form on lateral portions of the band portion 6a spaced from the central band portion 6b, as shown in FIG. 4. The central pile P, will thereby be maintained at a constant preselected width equal to the width w of the upper surface of the raised band portion 611 and the height h of the triangular cross section of the pile P above the upper edges 7 of the bars 7 will depend on the angle of repose of the granulated material forming the pile P which in turn will be proportional to the moisture content of the material. The heights of piles of granulated material such as foundry sand or the like for a specific grain size and having at the base width w equal to the width of the upper surface of the raised band portion 6b have been empirically established for various moisture contents of the material and in order to regulate the moisture content of the material to a desired moisture content the elevation of the frame 11 is adjusted by means of the spindle 12 in such a manner that the last of the photo-electric cells 9a is located above the upper edges 7 of the bars 7 a distance it equal to the empirically established height for the selected moisture content of the material. If the moisture content of the material fed from the container 1 onto the moving band is smaller than the desired moisture content, the height of the pile P will be smaller than the adjusted distance of the photo-cell 9d from the upper edges of the bars 7, and the valves connected to the various photo-cells will be operated by the latter to regulate the addition of water to the granulated material in the container 1 until the apex of the pile P is at the elevation of the last photo-cell 9d. The adjusted elevation of the last photo-cell 9d determines the total amount of water fed into the sand before the latter is dropped onto the transporting band and the thus adjusted amount of water will result in the desired moisture content of the material. Since the base of the pile P is maintained at a constant width, the result obtained will be substantially independent from the amount of material fed onto the transporting band 8. The properly moistened material is fed from the right end of the transporting band 6, as viewed in the drawing, by means not shown in the drawing to a place of use.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of method and apparatus for measuring and adjusting the moisture content of granular material such as foundry sand and the like differing from the types described above.

While the invention has been illustrated and described as embodied in a method and apparatus for measuring and adjusting the moisture content of granular material during continuous transporting of the same, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Thus, for instance, the moistening agent may be fed in another way than as above described into the granular material, for instance the pipes Ilia-13d may feed the water in the form of sprays into the stream of sand between the outlet end of the container 1 and the sieve 2. Also, the transportingmeans may be constructed in a manner different from the manner described above, and it is essential only that upstream of the sensing means a pile of granular material of triangular cross section and having at the base a selected width is maintained.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method for measuring and adjusting the moisture content and therewith the formability of granular material such as foundry sand and the like comprising the steps of dropping the granular material in moistened condition and in a thin stream onto a surface extending substantially normal to said stream; continuously moving said surface in a direction substantially normal to said stream so that the material will form on said surface a continuous pile of triangular cross section in which the angles of the triangular cross section will depend on the angle of repose of the material, which angle of repose will in turn be proportional to the moisture content of the material; maintaining the base of said pile at a constant preselected width so that the height of the pile will depend on the angle of repose; measuring the height of said pile thus formed; and regulating the moisture content of the material before dropping it onto the surface in dependence on the measured height of said pile of preselected width.

2. A method as set forth in claim 1, wherein said step of maintaining the base of the pile at a constant width comprises the step of moving excess material beyond the constant width in opposite directions away from said pile during movement of the latter with said surface in said direction.

3. An apparatus for continuously measuring and adjusting the moisture content and therewith the formability of granular material such as foundry sand and the like comprising, in combination, elongated transporting means having an upper substantially horizontal surface and being movable in substantially horizontal direction; feeding means for dropping granular material in a stream of material from above onto a central portion of said upper surface of said transporting means while continuously moving the latter in said direction, so that the material will form on the transporting means a continuous pile of triangular cross section having its base on said surface; engaging means engaging said pile in the region of its base so as to maintain the width of said base at a preselected constant Width, whereby the height of the pile will depend on the angle of repose of the moist granular material; measuring means arranged downstream of said engaging means for measuring the height of said pile having a base of a preselected width; and means in the region of said feeding means connected to and co-operating with said measuring means for feeding a moistening agent into the material for regulating the moisture content of the granular material before the latter is dropped onto said upper surface of the transporting means.

4. An apparatus as set forth in claim 3, wherein said transporting means include support means, a pair of rollers turnably mounted on said support means, and an endless band wound about said rollers and having an upper run onto which the material is dropped by said feeding means.

5. An apparatus as set forth in claim 4, wherein said endless band has a raised central portion extending in longitudinal direction of said band and having a width equal to said preselected width of said base and an upper horizontal surface forming said upper surface of said transporting means.

6. An apparatus as set forth in claim 5, wherein said engaging means for maintaining the width of said base of said pile constant comprises stripper means arranged at opposite sides of said raised portion of said band and stationary in direction of movement of said band.

7. An apparatus as set forth in claim 6, wherein said stripper means include a pair of limiting bars respectively extending along opposite sides of said raised :band portion and having each an upper edge slightly above said upper horizontal surface of said raised band portion, and a plurality of stripper bars extending respectively from outer faces of said limiting bars at an acute angle inclined thereto.

8. An apparatus as set forth in claim 7, wherein said upper edge of each limiting bar is beveled, and wherein said limiting bars are adjustable in vertical direction relative to said band.

9. An apparatus as set forth in claim 3, wherein said measuring means includes at least one photo-electric cell.

10. An apparatus as set forth in claim 9 and including mounting means mounting said photo-electric cell adjustable in vertical direction relative to said upper surface of said transporting means.

11. An apparatus as set forth in claim 3, wherein said measuring means include a plurality of photo-electric cells arranged spaced from each other in said direction and respectively spaced in vertical direction at different distances from said upper surface of said transporting means.

12. An apparatus as set forth in claim 11, wherein said distances of said photo-electric cells from said upper surface increase in direction of movement of said transport- 111g means.

13. An apparatus as set forth in claim 12 and including mounting means mounting said photoelectric cells adjustable in vertical direction relative to said upper surface of said transporting means.

14. An apparatus as set forth in claim 13, wherein said means for regulating said moisture content of said granular material include conduit means for feeding a moistening agent into said granular material before it is dropped onto said transporting means, adjustable valve means in said conduit means, and means connecting said photoelectric cells to said valve means for controlling flow of the moistening agent through said conduit means in dependence on the height of the pile measured by said measurmg means.

References Cited UNITED STATES PATENTS 2,273,126 2/1942 McGillin 134-57 2,709,843 6/1955 Hartley 13457 3,082,497 3/1963 Michalowski 137-57 3,151,368 10/1964 Dietert 134-57 3,221,381 12/1965 Nutter 13457 ROBERT B. REEVES, Primary Examiner. K. N. LEIMER, Assistant Examiner. 

1. A METHOD FOR MEASURING AND ADJUSTING THE MOISTURE CONTENT AND THEREWITH THE FORMABILITY OF GRANULAR MATERIAL SUCH AS FOUNDRY SAND AND THE LIKE COMPRISING THE STEPS OF DROPPING THE GRANULAR MATERIAL IN MOISTENED CONDITION AND IN A THIN STREAM ONTO A SURFACE EXTENDING SUBSTANTIALLY NORMAL TO SAID STREAM; CONTINUOUSLY MOVING SAID SURFACE IN A DIRECTION SUBSTANTIALLY NORMAL TO SAID STREAM SO THAT THE MATERIAL WILL FORM ON SAID SURFACE A CONTINUOUS PILE OF TRIANGULAR CROSS SECTION IN WHICH THE ANGLES OF THE TRIANGULAR CROSS SECTION WILL DEPEND ON THE ANGLE OF REPOSE OF THE MATERIAL, WHICH ANGLE OF REPOSE WILL IN TURN BE PROPORTIONAL TO THE MOISTURE CONTENT OF THE MATERIAL; MAINTAINING THE BASE OF SAID PILE AT A CONSTANT PRESELECTED WIDTH SO THAT THE HEIGHT OF THE PILE WILL DEPEND ON THE 